When we need a MySQL database for a site it's best to create a database and a user with privileges on that database alone.
First we need to log in to MySQL as root to set everything up. Be prepared to enter the root password.
mysql -u root -p
Next we'll create the database.
CREATE DATABASE my_new_database;
Then we'll create a user and grant access to that database.
CREATE USER 'my_new_user'@'localhost' IDENTIFIED BY 'password';
GRANT ALL PRIVILEGES ON my_new_database.* TO 'my_new_user'@'localhost';
Then let's flush the privileges before we leave.
To see a list of users, run this query.
SELECT User FROM mysql.user;
To check privileges for a particular user, run this query.
SHOW GRANTS FOR 'user'@'localhost';